Pros
I work in BT Advise US&C. The people there are phenomenal, and the projects are truly opportunities in global IT that you wouldn't find anywhere else. I continue to stay because my projects keep me highly engaged and interested in my work. You can work at home when not on an on-premises assignment. A good number of projects allow this flexibility. Because you are typically working with global customers, it doesn't necessarily make sense to have you on-premises all the time. The in-role promotion process is clearly spelled out, though perhaps a bit difficult to attain at higher levels.
Cons
BT Advise US&C was the result of an acquisition. It's fair to say that BT has destroyed everything good about that former company - but the management team in Advise is almost 100% from that acquisition. Management doesn't clearly articulate what the plans are, and how the consulting practices are formulated. The company is obsessed with current-quarter financials, with little or no view of the future. There is no such thing as "investment" in BT Advise. Certain consulting practices have been decimated by layoffs, most recently June 2014. If you are thinking of joining BT Advise, make sure you aren't going to be a "lone wolf", which will make you the only consultant in the US & Canada doing what you do. Want a promotion to a new job? There are very little job opportunities in Advise US&C. You will have to move to another BT Global Services business unit if you want bigger and better. Professional Development (training) is on your own dime. Worse, if you need to pick up a new skill set for a project, you will do so on the customer's time. Your laptop (called the BT WebTop) is a fixed global image of Windows 7 that is unbelievably locked down and featureless. You have very little flexibility or options for additional software. It is such an embarrassment to an IT professional that I refuse to let my clients see it. This is the first job I have had to go buy a personal laptop just so I can do my job. Compound that with an internal BYOD policy of "we have implemented the Good client for email on mobile phones" (go read any review of that product...) and you basically have few choices to do your job on anything but a real Windows laptop. Management is absolutely tone-deaf on this issue. The company professes to have world-class unified communications services and products (and they are stellar), but its internal implementation of Lync is hopelessly crippled. It is nothing short of embarrassing to be on a Lync project. They have been promising for three years to fix this, but nothing so far.